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UNIX in a Nutshell: System V Edition

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The Bourne Shell and Korn Shell
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4.9 Restricted Shells

Restricted shells can be invoked in any of the following ways:


rksh
	

Korn shell



ksh -r


set -r



rsh
	

Bourne Shell



set -r

Restricted shells can also be set up by supplying rksh and rsh in the shell field of /etc/passwd or by using them as the value for the SHELL variable.

Restricted shells act the same as their non-restricted counterparts, except that the following are prohibited:

  • Changing directory (i.e., using cd ).

  • Setting the PATH variable. rksh also prohibits setting ENV and SHELL.

  • Specifying a / for command names or pathnames.

  • Redirecting output (i.e., using > and >> ).

Shell scripts can still be run, since in that case the restricted shell will call ksh or sh to run the script.


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